A blood coagulation analysis device is known which analyzes blood coagulation time by adding a reagent for coagulating blood to a blood specimen, preparing a coagulation analysis sample, and optically measuring a coagulation reaction process of the coagulation analysis sample. In the blood coagulation analysis, there is a case where the blood coagulation analysis is not accurately performed by an optical measurement being affected by interference substances (substances coexisting in the sample together with the target substance to be tested and optically interfering with the measurement of the target substance) such as hemoglobin, bilirubin, and chyle contained in the coagulation analysis sample. If light having a long wavelength is used for measurement, although it is not affected by hemoglobin and bilirubin, the influence of chyle also decreases, on the other hand, the measurement sensitivity decreases. Therefore, in the blood coagulation analysis device of the related art, light having a wavelength around 660 [nm], which is less susceptible to the influence of interference substances moderately and has suitable measurement sensitivity, is used for measurement. However, even when light having a wavelength around 660 [nm] is used for measurement, the influence of chyle cannot be ignored. Therefore, efforts have been made to quantify the degree to which these interference substances are contained in the specimen and to eliminate the influence thereof.
For example, PTL 1 discloses a technique which measures the content degree of interference substances using optical information (lag phase) from mixing of a coagulation analysis reagent into the blood specimen until before the coagulation reaction is shown by light from a coagulation analysis sample obtained by mixing a coagulation analysis reagent into a blood specimen is received by a first light receiving portion to acquire temporal optical information. According to this method, since the degree of the interference substance in the blood specimen can be measured and the blood specimen is diluted with the coagulation analysis reagent, a measurement range of the degree of the interference substance can be expanded.
In addition, PTL 1 described above also discloses a technique for acquiring optical information by receiving light from the blood specimen before a coagulation analysis reagent is mixed into the blood specimen. According to this method, since the content degree of interference substances in the blood specimen can be measured before the coagulation analysis reagent is mixed with the blood specimen, in a case where the content degree of interference substances in the blood specimen is large, the mixing of the coagulation analysis reagent into the blood specimen can be stopped. Therefore, wasteful consumption of the coagulation analysis reagents can be suppressed.
PTL 2 discloses a technique which adjusts an amplification rate of a detection circuit by a light source having a plurality of wavelengths and electronic volumes corresponding thereto in order to detect the presence or absence, type, the content degree, or the like of interference substances in a specimen before mixing a coagulation analysis reagent into the blood specimen.